MATHUSLA (Massive Timing Hodoscope for Ultra-Stable neutraL pArticles) [1]}, [2]}, [3]} is a proposed large-scale dedicated Long-Lived Particle (LLP) detector to be situated at CERN near the CMS detector. It will be able to reconstruct the decay of neutral LLPs, produced in HL-LHC collisions in CMS, as displaced vertices (DV) in a near-zero-background environment. The physics case for LLP searches at the HL-LHC in general and MATHUSLA in particular was explored in detail in [4]}. MATHUSLA would be able to extend the sensitivity in long lifetime and LLP cross section by several orders of magnitude compared to the main LHC detectors alone, depending on the production and decay mode.
In particular, it would allow searches for LLPs with lifetimes near the upper Big Bang Nucleosynthesis bound set by cosmology, and also play a vital role in the search for Dark Matter (DM).
MATHUSLA is therefore crucial in exploiting the full physics potential provided by existing LHC collisions.
